||The Session Initiation Protocol (SIP) was conceived for internet telephony which is now viewed as an enabler of converged communications across distributed networked entities. Of particular interest to us was the SIP-based Presence protocol. Depending on the type of presence information, a variety of services can be built on top of it. These range from simple notification services to more complex dynamic discovery and load balancing. As a logical enhancement of Presence protocol, the SIP-based Discovery protocol has been examined which has been developed for the Multi-Channel Service Oriented Architecture (MCSOA). This work gives details of validated Colored Petri Net models of SIP based Presence and Discovery protocols. By using the modular and hierarchy mechanism of our adopted modeling approach, other services and applications for mobile computations that make use of presence or dynamic discovery can be easily built on the top of the presented model.